DE68925803T2 - Atherectomy system - Google Patents

Description

The present invention relates to an atherectomy system for drilling, picking up and removing an obstruction from within a patient's blood vessel.

As we age, a large percentage of the population develops atherosclerotic arterial obstructions, resulting in reduced blood flow. The disruption of blood flow that these obstructions cause can lead to the formation of blood clots, which further reduce or block blood flow. When this process occurs in the coronary arteries, it is called a heart attack. Currently, such obstructions are bypassed by surgically creating a bypass or they are treated with a catheter equipped with a balloon that is passed through the arterial system over a flexible guidewire into the obstruction and then inflated to widen the lumen of the obstruction (angioplasty). Some of the problems with angioplasty are that it injures the artery wall, creates a coarse lumen, and is ineffective in a considerable number of cases. Furthermore, angioplasty does not remove the obstructing material from the arterial system, and therefore, in the event of a heart attack, immediate angioplasty carries the risk that the blood clot may dislodge and move downstream, causing new blockages.

EP-A-0254414 discloses an atherectomy system for drilling, picking up and removing an obstruction from the interior of a patient's blood vessel, comprising a flexible guide wire that can be inserted into the vessel, a flexible rotating catheter that can be arranged rotatably over this flexible guide wire and introduced into the vessel and has at its distal end a rotating drilling means for making a circular cut in an obstruction lying in front of it and coupling means at its proximal end, a continuous channel for receiving the drilled out obstruction material, which is defined between the flexible rotating catheter and the flexible guide wire, the relative movement between the flexible rotating catheter and the flexible guide wire supporting the movement of the received obstruction material in the proximal direction through this continuous channel, and a cuff in which the flexible catheter is slidably arranged, this cuff having an elongated tongue that protrudes from its distal end.

However, a problem with this atherectomy system is that it is difficult to treat eccentric lesions in larger arteries unless a larger diameter catheter is used, which increases the size of the initial puncture wound and can injure the patient.

From EP-A-238217 an atherectomy system is also known which comprises a cutting device mounted in a cylindrical housing which has a cutout on one side at its distal end which receives the obstruction to be removed by inflating a balloon attached to the outside of the housing opposite the opening. A problem with this system is that it is difficult to steer the housing so that the opening is positioned over the obstruction before the balloon is inflated.

Patent EP-A-347098, which is relevant under Art. 54(3) EPC, discloses another type of atherectomy system. This atherectomy system comprises a catheter of substantially the same type, but the tongue at the distal end of the catheter cuff has the sole purpose of protecting the arterial wall, which does not definitively receive the catheter.

According to the invention, an atherectomy system is provided for drilling, receiving and removing an obstruction from the interior of a patient's blood vessel, which is characterized by a flexible guide wire which can be introduced into the vessel, a flexible rotating catheter which is rotatably arranged over this flexible guide wire and can be introduced into the vessel and has at its distal end a rotating drilling means for making a circular cut in an obstruction lying in front of it and coupling means at its proximal end, a continuous channel for receiving the drilled obstruction material which is defined between the flexible rotating catheter and the flexible guide wire, wherein the relative movement between the flexible rotating catheter and the flexible guidewire to assist in the movement of the received obstruction material in a proximal direction in said continuous channel, and a sleeve in which the flexible catheter is slidably disposed, said sleeve having an elongated tongue extending from its distal end, characterized in that the tongue defines an eccentrically deflected path for the boring means to move along within the vessel and has a cross-section partially encompassing and unambiguously enclosing the flexible catheter.

The preferred atherectomy catheter of the invention can be inserted and advanced into an artery over a flexible guidewire. The flexible catheter is provided with a reaming means at its distal end to ream out and remove obstructive material and create a smooth lumen without destroying the artery wall. The catheter can be slid within an eccentrically deflecting cuff which defines the path of the catheter in the vessel to selectively direct the reaming means into the obstruction. This allows treatment of eccentric lesions and use of the system in larger arteries without having to increase the diameter of the flexible catheter and associated puncture wound at the point of introduction of the system into the vessel.

A preferred embodiment of the invention will now be described, by way of example only with reference to the attached drawings, in which:

Fig. 1 schematically shows a general view of an atherectomy system that has been introduced in the groin area through the arterial system of a patient into his coronary artery,

Fig. 2 shows a longitudinal section through the atherectomy system. The middle section of the system is shown with a dashed line due to the limited space on the drawing sheet.

Fig. 3 is a bottom view of a distal portion of a first embodiment of the system,

Fig. 4 is a side view of a distal portion of the first embodiment in an artery prior to pressurizing an inflatable chamber through an inflatable tube and expanding an obstruction agent at the distal end of the flexible guidewire,

Fig. 5 is a cross-section through the first embodiment along the line 5-5 marked in Fig. 4 in an artery before pressurization of an inflatable chamber,

Fig. 5' a cross-section through the tongue of the first embodiment along the line 5-5 marked in Fig. 4 on an enlarged scale, wherein the reinforcing rib can be seen,

Fig. 6 is a side view of a distal portion of the first embodiment in an artery, with the inflatable chamber and the inflatable tube under pressure and the distal obstruction means expanded,

Fig. 7 is a cross-section through the first embodiment along the line 7-7 marked in Fig. 6 in an artery, with the inflatable chamber under pressure and the distal obstruction-forming means expanded,

Fig. 8 is a bottom view of a distal portion of a deflection cuff of a second embodiment of the system,

Fig. 9 is a cross-section through the deflection cuff with an inflation channel formed in its wall along the line 9-9 marked in Fig. 8,

Fig. 10 is a side view of a distal portion of a deflection cuff of the second embodiment of the system,

Fig. 11 is a cross-section through the barrier along the line 11-11 marked in Fig. 10.

Fig. 12 a cross-section through the tongue along the line 12-12 marked in Fig. 10,

Fig. 13 is a side view of a distal portion of the tongue of the second embodiment of the system with a pressurized inflatable chamber and a closed barrier,

Fig. 14 is a front view of a distal end of the tongue with a pressurized inflatable chamber and a closed barrier, and

Fig. 15 is a cross-section through the tongue of the second embodiment of the system along the line 15-15 marked in Fig. 13 in an artery, with a pressurized chamber which deflects the tongue.

Fig. 1 shows schematically a general view of an atherectomy system with a diversion cuff 10 inserted percutaneously (through the skin) into a femoral artery 11 of a patient in the groin region. The distal end of the system has been advanced through the arterial system to reach a working site in a coronary artery 12 and its proximal end remains outside the patient's body.

As shown in Fig. 2, the atherectomy system comprises several elongated members in a nested relationship, the vessel-entering end of which shall be referred to as "distal" and the other end as "proximal." In view of this, "distal direction" or "distal" shall indicate a general direction from the proximal end to the distal end and shall mean "proximal direction" or "proximal" an opposite direction.

As also shown in Fig. 2 (the same numbers are used to designate like or comparable parts throughout the figures), the distal portion of the system 10 is located in the diseased coronary artery 12 which contains an eccentric atherosclerotic obstruction 13. The middle portion of the system is shown by a dashed line 16 due to space limitations on the drawing sheet.

The system includes:

A flexible guide wire 17 that can be inserted through the human vascular system,

A flexible rotating catheter 15 rotatable and slidable over the guidewire, having a wall 20 defining a longitudinal channel 21. Attached to the distal end of the flexible rotating catheter is a reaming means in the form of a tubular blade 22. The tubular blade defines a through hole which forms a continuous channel with the channel 21 for receiving the obstruction material received in the through hole. Alternative suitable reaming means using radiation, heat or teeth are discussed in my above-cited copending applications.

Friction losses occurring between the flexible rotating catheter and a deflection cuff 26 place stress on the flexible rotating catheter and the motor. These friction losses are more pronounced in a corpulent patient where the system is inserted into the femoral artery at the groin and must assume a large curvature at the entry point due to the patient's protruding abdomen. To reduce these friction losses, the diameter of the proximal portion of the flexible rotating catheter decreases at a point indicated at 15' in Figure 2. Such a reduction in diameter does not affect the collection of obstructive material as long as a sufficiently large distal portion of the flexible rotating catheter of full diameter remains to collect the material. For example, a flexible rotating catheter for removing obstruction from peripheral arteries having a total length of 50 cm can be made with a 35 cm long, 2 mm diameter proximal portion and a 15 cm long, 3 mm diameter distal portion. However, if the obstruction is long, the location of the diameter transition point can be moved 15' proximally to increase the catheter's capacity to accommodate material.

A motor 24 has a hollow shaft 25 with a tapered distal end 30' which engages a coupling means in the form of a mating tapered seat 30 formed at the proximal end of the flexible rotating catheter.

The deflection cuff 26 includes a tongue with a deflection means that defines an eccentric path for the drilling means to move along inside the vessel. The cuff can also serve as an introduction means for the system into the artery, or it can be introduced through a separate introduction sheath. Moreover, the cuff can be shaped in a desired form to serve as a guide catheter to assist in conveying the flexible rotating catheter to the work site. The deflection cuff also includes a port 27 through which it receives contrast or irrigant/lubricant and releases it through its distal end at the work site. A seal 31 prevents the fluid from escaping through the proximal end of the cuff.

A rotatable connector 28 has a port 29 connected to the through-channel through the hollow shaft 25 and can be used to create a negative pressure in the through-channel to assist in drawing in and withdrawing the reamed obstruction material therein. The suction and a mechanical process resulting from the relative movement between the rotating inner wall of the through-channel and the fixed flexible guidewire effectively draw the reamed material into the through-channel for subsequent removal from the patient's body. At an early stage of the procedure, prior to collection of the obstruction material, the fluid path connecting the port 29 and the distal end of the flexible rotating catheter can serve as an alternative route for transporting fluids to the work site.

The flexible guide wire slides through a narrow fitting opening formed at the end of the rotating connector.

Fig. 3 to 7 show the distal end of an atherectomy system with a first embodiment of a diversion cuff for removing an obstruction from inside the vessel, the artery 12 of a patient, comprising:

the flexible guide wire 17',

the flexible rotating catheter 15 with a drilling means in the form of the tubular blade 22 at its distal end for drilling and for receiving obstruction material, which can be introduced into the vessel via the flexible guide wire,

a deflection sleeve 26 in which the flexible rotating catheter is rotatably and slidably disposed, and an elongated tongue 35 extending from the distal end of the deflection sleeve and defining an eccentric path in the vessel along which the flexible rotating catheter and the drilling means move and drill.

In the first embodiment, the tongue has a cross-section in the shape of an incomplete circle, shown in Figs. 5, 5' and 7, which clearly encloses the flexible catheter by enclosing slightly more than half of its circumference. The cross-section of the tongue is stabilized by reinforcing means in the form of semi-circular rib-like elements 46 (see Fig. 5'). The elements 46 are interconnected by a spine-like element 47 which contributes significantly to the strength and rigidity of the tongue by resisting twisting under the influence of a torque force while allowing bending of the tongue. Therefore, the elements 46 and 47, which may be made of a flat sheet material made of stainless steel, stabilize the cross-section of the tongue in such a way that the correct relationship between the cross-section of the tongue and the tubular blade is maintained, but the tongue can bend and conform to the curvature of the artery. They also enable the user to rotate the tongue within the artery to position or realign its tip with the open side toward the obstruction to be removed.

The tongue includes a selectively operable deflection means in the form of an inflatable chamber 42 for eccentrically deflecting it within the vessel to define the eccentrically deflected path for the flexible rotating catheter and the drilling means to move and drill along within the vessel. The tongue allows the user to position the drilling means along eccentric lesions and use the system for recanalization of larger arteries. Recanalization of larger arteries is accomplished by drilling while simultaneously deflecting the reaming means with the tongue to one side of the artery, then moving the reaming means back, rotating the cuff and tongue a fraction of a turn within the artery, re-deflecting the tongue by inflating chamber 42 and creating another passageway, repeating the process as necessary to create additional passageways. In this way, a large diameter artery can be cleared and recanalized through a smaller puncture wound in the vessel wall.

An inflatable tube 44 for inflating the chamber 42 is formed integrally with the chamber. When the chamber is inflated, the tube is also slightly inflated as shown in Fig. 6; however, prior to inflation, the tube remains flat (a vacuum may be applied to the tube to further reduce its dimensions) as shown in Fig. 4, thereby minimizing its contribution to the overall thickness of the diversion cuff structure and to the size of the puncture wound that will be required to introduce the structure into the patient's body.

The flexible guide wire 17' has a distal obstruction forming means in the form of a thin sheath over a core wire 67. The sheath and the core wire are connected together at their distal tip, and by pulling the core wire at the proximal tip relative to the sheath, arms 68 are formed which formed by numerous slots in the sheath. Obstacle-forming means as well as additional suitable flexible guide wire constructions are discussed in my above-cited co-pending applications.

In the second embodiment of the deflection collar 26', shown in Figures 8 to 15, the tongue 35 has a "U" shaped cross-section which acts to define an eccentrically deflected path in the vessel for the reaming means to travel along while keeping the arterial wall clearly out of that path, thereby minimizing the likelihood of cutting the arterial wall (see Figure 15).

The tongue of the second embodiment 35' has a selectively variable cross-section to facilitate its insertion in a collapsed position as shown in Figure 12 to minimize the size of the puncture wound required to introduce the system into the vessel. At the site of obstruction, the tongue deploys in response to inflation of an inflatable chamber 63 externally attached to a lower surface of the tongue 35' as shown in Figure 15. The inflatable chamber 63 also serves to deflect the U-shaped tongue toward the artery wall; however, if the tongue is deflected prior to deployment and contacts the wall, contact with the wall may interfere with the deployment process.

Optionally, a smaller inflatable chamber 43, as shown in phantom in Figure 15, may be inserted into the inflatable chamber 63 to deploy the tongue when it is inflated. Due to its smaller size, the chamber 43 is less likely to force the tongue against the wall. When the deployment process is complete, the inflatable chamber 63 may be inflated to effect deflection of the tongue. A channel 71 formed in a wall of the cuff 26', shown in Figures 8 and 9, has a distal end communicating with the chamber 63 to direct the inflation fluid thereto.

The tongue 35' has a barrier 61 at its distal end to minimize distal escape of obstruction material. The barrier can be selectively actuated by a distally constricted end 64 of the inflatable chamber 63, which acts as an actuator which, when inflated, brings the barrier into the position shown in Fig. 13 and closes it. Alternatively, a mechanical means in the form of a strip 62, preferably made of stainless steel, shown in dashed line in Fig. 13, can be used to close the barrier 61.

The present invention provides a method for removing an obstruction from a vessel using an atherectomy system, which comprises the following steps:

Inserting a flexible guidewire into an obstruction in a vessel (the technique of inserting guidewires through the vascular system is well known),

Advancement over the flexible guidewire of a flexible catheter with a reaming device at its distal end to the area surrounding the obstruction,

Drilling an initial lumen into the obstruction and collecting the drilled material into the catheter. Removing the drilling agent from the initial lumen and inserting a diversion tongue into it,

Advance the flexible catheter and drill out the obstruction along an eccentrically deflected path defined by the tongue. The extent of the deflection can be regulated by the inflation pressure of a chamber attached to the underside of the tongue.

If the diseased lumen is large enough to accommodate the tongue, the step of drilling an initial lumen can be omitted.

A vacuum can be applied to assist the mechanical process of collecting the drilled material into the continuous channel.

It should be noted that the atherectomy system can be manufactured in different diameters and lengths, depending on the size and location of the artery, for which it is intended and whether the system is to be used percutaneously (that is, through the skin) or intra-operatively (that is, when the vessel is surgically exposed to introduce the system into a vessel).

It can also be seen from the present application and the cited applications that the components of the atherectomy system can be made differently: the flexible catheter can be made of plastic or metal, and either version can be provided with an internal helical step. The reaming means can be a tubular blade, a heated tubular blade, or a radiation emitting means such as a light guide located on a wall of the flexible catheter and transmitting laser energy, or other means that reams out and accommodates an obstruction located in front of it. By combining a deflection cuff with specific features, a flexible catheter with specific features, and a flexible guidewire with specific features, a variety of different types can be created to tailor the characteristics of the system to the specific disease characteristics of an individual patient, which is helpful because the clinical presentation of arterial atherosclerotic obstructions varies in geometry, severity, and accessibility from patient to patient.

Claims (19)

1. Atherectomy system for drilling, picking up and removing an obstruction from the interior of a patient's vessel, comprising a flexible guide wire (17) that can be inserted into the vessel, a flexible rotating catheter (15) that can be arranged so as to be rotatable over this flexible guide wire (17) and inserted into the vessel and has a rotating drilling means (22) at its distal end for making a circular cut in an obstruction lying in front of it and coupling means (30) at its proximal end, a continuous channel for receiving the drilled out obstruction material, which is defined between the flexible rotating catheter (15) and the flexible guide wire (17), wherein the relative movement between the flexible rotating catheter (15) and the flexible guide wire (17) causes the movement of the picked up obstruction material in the proximal direction through said continuous channel, and a cuff (26) in which the flexible catheter is slidably arranged, said cuff having an elongated tongue (35, 35') projecting from its distal end, characterized in that the tongue (35, 35') defines an eccentrically deflected path for the coring means to move along within the vessel and has a cross-section which partially encompasses and clearly encloses the flexible catheter (15). 2. Atherectomy system according to claim 1, characterized in that the tongue (35) has a circular cross-section. 3. Atherectomy system according to claim 1, characterized in that the tongue (35) has a U-shaped cross-section. 4. Atherectomy system according to claim 1, characterized in that the tongue has a selectively variable cross-section in order to facilitate its introduction into the vessel. 5. Atherectomy system according to any one of the preceding claims, characterized in that the cross-section of the tongue is stabilized by reinforcing means (47). 6. Atherectomy system according to any one of the preceding claims, characterized in that the tongue (35) has a selectively operable deflection means for eccentrically deflecting said tongue in the vessel. 7. Atherectomy system according to any one of the preceding claims, characterized in that the diversion means comprises an inflatable chamber (42) attached to the underside of the tongue (35). 8. Atherectomy system according to any one of the preceding claims, characterized in that the tongue has a locking barrier (61) at its distal end. 9. Atherectomy system according to claim 8, characterized in that the locking barrier (61) is selectively actuable by mechanical means. 10. Atherectomy system according to claim 8, characterized in that the barrier (61) is selectively actuatable by inflatable chamber means (63). 11. Atherectomy system according to any of the preceding claims, characterized in that suction means at the proximal end of the through-channel can be used to pull the drilled-out obstruction material in the through-channel in a proximal direction. 12. Atherectomy system according to any one of the preceding claims, characterized in that the boring means consists of a rotating tubular blade (22). 13. Atherectomy system according to any one of the preceding claims, characterized in that the flexible catheter is a flexible rotating catheter. 14. Atherectomy system according to claim 13, characterized in that the flexible rotating catheter has a reduced cross-section at its proximal portion in order to reduce friction losses between the flexible rotating catheter and the cuff. 15. Atherectomy system according to any one of the preceding claims, characterized in that the drilling means is a radiation emitting device. 16. Atherectomy system according to any one of the preceding claims, characterized in that the flexible guide wire has radially extending distal obstruction-forming means (67, 68) to counteract distal movement of the obstruction material. 17. Atherectomy system according to claim 16, characterized in that the distal obstruction-forming means (67, 68) can contract elastically. 18. Atherectomy system according to claim 17, characterized in that the distal obstruction-forming means (67, 68) is selectively expandable. 19. Atherectomy system according to any one of the preceding claims, characterized in that means for introducing fluids into the vessel are connected to the cuff.